Process of making synthetic building blocks from lime



Patented Nov. 7, 1933 J IPROCESS OF "MAKING SYNTHETIC BUILD- ING BLOCKSFROM LIllIE Arthur Hugo 'Harrison, Gold Pines, Ontario, Canada, assignerto Carbonated Lime Processes Limited No Drawing. Application February13, 1932 Serial. No.v 592,851

6 Claims. (Cl. 1847.5)

This invention relates to the production of particles has a tendency toprevent the adhersynthetic building blocks from lime and relates ence-ofthe carbonated lime to the aggregate particularly to the process ofprior application, particles. The sized particles should be free SerialNo. 512,999, filed February 2, 1931, when from dust. The aggregate issoaked in water .5 the same is used for theproduction of blocks, so thatwhen it is mixed with the aerated slurry slabs or the like ofsubstantial thickness. it will not absorb water therefrom and releasethe It has been found that, when using the prior air. process for theproduction of blocks, slabs or the The particles of aggregate aresurrounded by like. having a substantial thickness or diameter, theaerated lime slurry which fills the voids be- 2111) there is difiicultyin wholly avoiding cracking of tween the aggregate particles. Molds ofperthe blocks. The length of the block is immaforated or porous materialare used to form the terial but with a diameter of, say, 6 or 8 inches,mixture into blocks of the required size and shape which is required inmany instances, there is a and the mixture is carbonated in these molds.definite tendency for the blocks to crack or check The perforated moldscontaining the mixture are 351-5 leaving a product which is not entirelypreferably loaded on trucks in such a Way as to satisfactory. permitfree circulation of gas about each mold The object of this invention isthus to overand the trucks pass into a carbonating tunnel. come thisdifficulty and to so improve the prior or chamber which is heated tomaintain a drying process that blocks of the desired thickness ortemperature therein. Substantially pure carbon ?-;21) diameter may beobtained without fear of crackdioxide gas is kept in continuouscirculation ing, during the process of carbonation. through the tunnelto cause the carbonation of A further object of the invention is toprovide the relatively thin layer of aerated lime slurry a process ofproducing on these synthetic blocks a about the aggregate particles. Asthe carbonatstrong, smooth surface which will be substaning reactionproceeds Water is liberated and is tially resistant to damage inhandling or use, and removed from the block under the influence of whichwill greatly decrease the tendency for the the drying temperature in thechamber. blocks to absorb moisture. It will be observed that the amountof lime In the prior process referred to an aerated in the blocks to becarbonated is much less than slurry of lime is subjected to the actionof carbon in the prior process and that this lime is in i30 dioxide gasin a heated chamber to carbonate the relatively thin portions or layers.Cracking or lime and form a highly porous mass or block of other flawsin the blocks are thus avoided. Morecalcium carbonate. In accordancewith the presover, as the lime of the slurry carbonates, it tends entinvention, when making blocks of a subto fill the exposed cells in theporous calcium carstantial diameter this porous calcium carbonate isbonate aggregate bonding the whole into a unicrushed to provide anaggregate which is intary cellular structure. .90

corpcrated with aerated lime slurry and the The carbon dioxide gasshould be substantially mixture is subjected to the action of carbonpure and free from sulphur, which, if present,- dioxide gas in a heatedchamber to carbonate the reacts to form compounds which weaken the limeand cause it to harden about the porous blocks.

1 40 calcium carbonate particles. In this way the These blocks areuseful for many purposes and cracking of the blocks is avoided and thefinished particularly in the building arts. In some cases blocks containonly calcium carbonate interthe surface of the blocks is notsufiiciently hard spersed throughout with cells. The porous charanddurable to resist the stresses to which the acter of the materialpermits the carbonation to blocks are subjected in handling and/or use.

proceed to completion and the aggregate being Moreover, for somepurposes it is desirable to of the same composition as the slurry, thebond have the surface of the blocks more resistant between the newlycarbonated lime and the agto absorption. This invention thuscontemplates gregate is a secure one. so improving the blocks as to meetthese require- The size of the particles to which the porous ments. 6D li m carbonate is crushed may vary widely The cellular blocks of calciumcarbonate are but it is desirable that the particles be free from givena coating of l m hydrate a e a a n dust. Particles passing a screen ofone inch subjected to the action of carbon dioxide in the opening andbeing retained on a screen having a heated carbonating chamber to changethe hyone-hall inch opening are illustrative of the size drated limecoating into calcium carbonate. The of the aggregate particles. Dustadhering to the thickness of the coating may vary within sub- 1.10

stantial limits. The thicker the coating, the longer it will take tocomplete the carbonation. In some cases, what may be referred to as awash or paint coat will be sumcient. In other cases the hydrated limeputty or mortar may be ap plied in a coating A; or inch in thickness.

The surface so formed is strong, smooth and more or less shiny. It isresistant to absorption.

It will be apparent that these blocks consist of a core comprising cellsbonded together with calcium carbonate and a surface coat of solidcalcium carbonate.

I claim:

1. A process of making cellular blocks of calcium carbonate whichcomprises incorporating cellular particles of calcium carbonate with anaerated slurry of lime, molding the mixture and subjecting the moldedmass to the action of carbon dioxide gas in a heated chamber.

2. A process of making cellular synthetic building blocks whichcomprises carbonating an aerated slurry of lime, crushing the carbonateso formed, incorporating particles of the cellular carbonate in anaerated lime slurry, placing the mixture in porous molds and carbonatingthe lime in said slurry to harden the mass.

3. A process of making cellular building blocks from lime whichcomprises simultaneously drying and carbonating an aerated slurry oflime,

crushing the carbonated mass to form porous particles surrounding a massof said particles with an aerated lime slurry which fills the voids inthe mass and subjecting the mixture in porous molds to the action ofcarbon dioxide gas in a heated chamber to form unitary blocks ofcellular calcium carbonate.

4. A process of making cellular blocks of calcium carbonate whichcomprises incorporating cellular particles of calcium carbonate with anaerated slurry of lime, molding the mixture, subjecting the molded massto the action of carbon dioxide gas in a heated chamber to harden themass, then applying a coating of calcium hydrate to the blocks andchanging the calcium hydrate to calcium carbonate.

5. A process of making light weight blocks of calcium carbonatewhichcomprises subjecting a mixture of cellular particles of calciumcarbonate and an aerated lime slurry to the action of carbon dioxide gasin a heated chamber to harden the mass, coating the surface of thehardened mass with calcium hydrate and carbonating the latter in aheated chamber.

6. A light weight block comprising a core of cellular calcium carbonateand a surface coating of solid calcium carbonate.

ARTHUR HUGO HARRISON.

